- Copper(I) mediated radical polymerisation of uridine and adenosine monomers on a silica support
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Copper(I) mediated radical polymerisation is used to polymerise uridine and adenosine substituted methacrylates onto a silica surface giving supported polymers with potential as re-usable templates and for interaction with nucleic acids.
- Marsh,Khan,Garcia,Haddleton
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- Atom transfer radical polymerization from nanoparticles: A tool for the preparation of well-defined hybrid nanostructures and for understanding the chemistry of controlled/"living" radical polymerizations from surfaces
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Structurally well-defined polymer - nanoparticle hybrids were prepared by modifying the surface of silica nanoparticles with initiators for atom transfer radical polymerization and by using these initiator-modified nanoparticles as macroinitiators. Well-defined polymer chains were grown from the nanoparticle surfaces to yield individual particles composed of a silica core and a well-defined, densely grafted outer polystyrene or poly(methyl methacrylate) layer. In both cases;, linear kinetic plots, linear plots of molecular weight (Mn) versus conversion, increases in hydrodynamic diameter with increasing conversion, and narrow molecular weight distributions (Mw/Mn) for the grafted polymer samples were observed. Polymerizations of styrene from smaller (75-nm-diameter) silica nanoparticles exhibited good molecular weight control, while polymerizations of methyl methacrylate (MMA) from the same nanoparticles exhibited good molecular weight control only when a small amount of free initiator was added to the polymerization solution. The difference in polymerization behavior for styrene and MMA was ascribed to the facts that styrene undergoes thermal self-initiation while MMA does not and that termination processes involving freely diffusing chains are faster than those involving surface-bound chains. The polymerizations of both styrene and MMA from larger (300-nm-diameter) silica nanoparticles did not exhibit molecular weight control. This lack of control was ascribed to the very high initial monomer-to-initiator ratio in these polymerizations. Molecular weight control was induced by the addition of a small amount of free initiator to the polymerization but was not induced when 5-15 mol % of deactivator (Cu(II) complex) was added.
- von Werne,Patten
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- Mechanically reinforced silica aerogel nanocomposites via surface initiated atom transfer radical polymerizations
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Here we report the preparation of mechanically robust silica aerogel polymer nanocomposites using surface-initiated atom transfer radical polymerization. This approach was used to grow poly(methyl methacrylate) (PMMA) with low polydispersities and establish the first structure-property relationship between the grafted PMMA molecular weight and bulk physical properties of the hybrid aerogel.
- Boday, Dylan J.,Keng, Pei Yuin,Muriithi, Beatrice,Pyun, Jeffrey,Loy, Douglas A.
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- Surface-initiated living radical polymerization from narrowly size-distributed silica nanoparticles of diameters less than 100 nm
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Surface-initiated atom transfer radical polymerizations (ATRP) from narrowly size-distributed silica nanoparticles (SiNPs) of diameters less than 100 nm were investigated. Two methods were used for the preparation of the SiNP cores: one was the reverse-micelle technique, which gave monodisperse SiNPs of average diameter 55 nm, and the other was the lysine-addition technique, which gave nearly monodisperse SiNPs of average diameter 15 nm. These nanoparticles were surface-modified with a triethoxysilane derivative containing an ATRP-initiating group. The surface-initiated ATRP of methyl methacrylate (MMA) mediated by a copper complex was carried out with the initiator-fixed SiNPs in the presence of a "sacrificial" free initiator. Well-defined poly(methyl methacrylate) (PMMA) brushes of a target molecular weight were successfully grafted with a surface density as high as 0.4-0.8 chains/nm 2. These core-shell hybrid particles were highly dispersible, without any aggregation, in various solvents for PMMA. Because of the exceptionally high uniformity and perfect dispersibility, these hybrid particles formed two- and three-dimensional ordered arrays at the air-water interface and in suspension, respectively.
- Ohno, Kohji,Akashi, Tatsuki,Huang, Yun,Tsujii, Yoshinobu
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- Mannosylated Poly(ethylene imine) Copolymers Enhance saRNA Uptake and Expression in Human Skin Explants
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Messenger RNA (mRNA) is a promising platform for both vaccines and therapeutics, and self-amplifying RNA (saRNA) is particularly advantageous, as it enables higher protein expression and dose minimization. Here, we present a delivery platform for targeted delivery of saRNA using mannosylated poly(ethylene imine) (PEI) enabled by the host-guest interaction between cyclodextrin and adamantane. We show that the host-guest complexation does not interfere with the electrostatic interaction with saRNA and observed that increasing the degree of mannosylation inhibited transfection efficiency in vitro, but enhanced the number of cells expressing GFP by 8-fold in human skin explants. Besides, increasing the ratio of glycopolymer to saRNA also enhanced the percentage of transfected cells ex vivo. We identified that these mannosylated PEIs specifically increased protein expression in the epithelial cells resident in human skin in a mannose-dependent manner. This platform is promising for further study of glycosylation of PEI and targeted saRNA delivery.
- Abdouni, Yamin,Becer, C. Remzi,Blakney, Anna K.,Bouton, Clément R.,Liu, Renjie,McKay, Paul F.,Shattock, Robin J.,Yilmaz, Gokhan
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p. 2482 - 2492
(2020/07/17)
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- COMPOSITE PARTICLE-CONTAINING IMAGING AGENT FOR RENAL FUNCTION DIAGNOSIS
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PROBLEM TO BE SOLVED: To provide a novel imaging agent suitable for kidney function visualization. SOLUTION: The invention provides an imaging agent for renal function diagnosis which contains composite particles, wherein the composite particle is a composite particle in which a polymer graft chain binds on a particulate surface, the graft density of the polymer graft chain is 0.1 chain/nm2 or more, and the number average molecular weight (Mn) of the polymer graft chain is 30,000 or more. MR is used for the microparticle; iron, cobalt, alloy, iron oxide, or the like is used for measurement. If it is an optical image, an inorganic particle which may be or may not be a magnetic material or the like, or an organic coloring pigment or fluorescent pigment bound to or enclosed in a microparticle is used. SELECTED DRAWING: Figure 5 COPYRIGHT: (C)2016,JPO&INPIT
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Paragraph 0051; 0052; 0053
(2017/06/08)
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- Liquid crystal mono- and nano-layers covalently bonded to silicon and silica surface for alignment of LC layers
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We synthesized two types of liquid crystalline nano-layers covalently bonded to Si and Si/SiO2 wafers. Monolayers of terminal and lateral low molecular weight mesogens exhibit spontaneous homeotropic orientation, while planar orientation is obtained by means of rubbing process. On the other hand a novel polymer liquid crystal nano-layer, obtained via atom transfer radical polymerization (ATRP) of acrylate monomer from Si/SiO2 surface, exhibits planar orientation of liquid crystalline side chain moieties. Structure of such novel composites was confirmed by optical studies as well as spectroscopic methods, including ellipsometry. The goal was to obtain low molecular weight liquid crystals alignment just from the mentioned above, modified surfaces. Copyright Taylor & Francis Group, LLC.
- Stanczyk, Wodzimierz A.,Szelg, Anna,Kurjata, Jan,Nowinowski-Kruszelnicki, Edward,Walczak, Andrzej
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scheme or table
p. 18 - 27
(2011/04/27)
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- Silicon compound
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The present invention provides a novel silicon compound represented by Formula (1) having a living radical polymerization initiating ability for addition-polymerizable monomers and a polymer obtained using the same. The above polymer can provide an organic-inorganic composite material having a distinct structure. wherein R1 is hydrogen, alkyl, aryl or arylalkyl; R2 and R3 are alkyl, phenyl or cyclohexyl; and A is a group having an ability to initiate polymerization of a monomer.
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Page/Page column 80
(2008/06/13)
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